1. Field of the Invention
The present invention relates to an evaluation method for pneumatic tires and a system thereof, for evaluating an adverse effect of a temperature of a pneumatic tire, such as deterioration.
2. Description of the Related Art
Conventionally, as a method or a device for evaluating deterioration of a pneumatic tire, for example, there are known a method for estimating a secular change of tire disclosed in Japanese Patent Publication No. 2005-47295 (Patent Document 1), a tire heat deterioration detection sensor disclosed in PCT Patent Publication No. WO2003-100370 (Patent Document 2) and a vehicular ,diagnostic system disclosed in Japanese Patent Publication No. 2005-227141 (Patent Document 3).
The method for estimating a secular change of a tire disclosed in Patent Document 1 defines a tire model formed by dividing a tire into many elements and a model of energy (including thermal energy and elapsed time) applied to the tire model, performs stress calculation including breakdown parameters and drag calculation for destructive force and estimates tire secular changes (lifetime) based on physical quantities of these calculation results. This method provides estimation of tire secular change performance by a comparison between tire breakdown parameters and drag, thus making an analysis according to tire usage.
The tire heat deterioration detection sensor disclosed in Patent Document 2 includes a magnetic circuit constituting body which is mounted at a required portion of a tire and forms a closed magnetic circuit and a magnetic sensor for detecting a leaking magnetic field from the magnetic circuit constituting body, and has such properties that the leaking magnetic field increases when a temperature of the magnetic circuit constituting body rises or heat deterioration advances.
According to such a tire heat deterioration detection sensor, the magnetic sensor for detecting a leaking magnetic field from the magnetic circuit constituting body mounted at a required portion of a tire or detecting a magnetic field from a composite magnet is configured so as to detect a change in the magnetic characteristics of the magnetic circuit constituting body or the composite magnet and to change magnetic characteristics of the magnetic circuit constituting body or the composite magnet, depending on the magnitude of temperature or heat deterioration of a required portion of a tire. This makes it possible to grasp the magnitude of a temperature or heat deterioration of a required tire portion from a magnetic flux density detected by the magnetic sensor and to detect excessive magnitude of temperature or heat deterioration, thus warning a driver of the abnormal state for safe vehicle driving.
The vehicular diagnostic system disclosed in Patent Document 3 is a system which diagnoses deterioration or abrasion of vehicle consumables including tires and displays the diagnostic results on a screen of an on-vehicle display. Data to be collected includes tire average temperatures and tire maximum temperatures in one-day driving.
This system does not simply display diagnostic results of vehicle consumables on the screen nor simply display the driving behaviors of a driver on a screen, but includes the driving behaviors in the diagnostic elements for the magnitude of abrasion for display on a screen, thus attaining intuitive grasping for economical and safety driving by correlating the diagnostic results of vehicle consumables with the driving behaviors.                Patent Document 1: Japanese Patent Publication No. 2005-47295        Patent Document 2: PCT Patent Publication No. WO2003-100370        Patent Document 3: Japanese Patent Publication No. 2005-227141        